Pacific Tugboat Service, a member of the Port of San Diego's Green Business Network, has converted its fleet of 20 vessels. Shore power, also known as cold ironing, is the process of switching from a ship's onboard diesel power supply to shore-based electrical power while the ship is at the dock. This process reduces polluting air emissions and noise levels from idling engines. "I think the Green Business Network taught us is that we're not just a small business trying to make a living on the Bay, but we're a neighbor," said Pacific Tugboat Service Vice President Stephen Frailey.